Intel i815EP.

A late entry into the PC-133 SDRAM chipset comparison is Intel’s recently released i815EP chipset. Essentially the i815EP is the i815e but with the integrated i752 graphics controller removed (or disabled) and is sold at a lower price to the i815e.

Like the i815e, the i815EP owes much of its existence to the turmoil found in Intel’s chipset strategy thanks to the Rambus RDRAM compatible i820 chipset. In many respects the i815 fills much of the gap left by the i440BX by offering a PC-133 compatible chipset with just an AGP slot for the graphics accelerator.

The i815EP is the next example in how Intel developed the low-end i810 line into a credible mid-range to high-end chipset. It was well known that the integrated i810 line of chipsets offered good memory performance coupled to high levels of stability, their only shortcoming being the lack of a dedicated AGP 4X slot. Thus Intel developed the i815e and i815EP from the i810 range by adding AGP 4X and support for PC-133 SDRAM (the i810e supported 133 MHz FSB Pentium IIIs but only with PC-100 SDRAM), and other features.

Chipset Design.

As the i815EP was based upon the i810 family of chipsets, it follows a different architecture to earlier Intel chipsets such as the i440BX and the other VIA chipsets featured in this article. Instead of the familiar North and South Bridge controller design, the i815EP uses Intel’s Accelerated Hub Architecture design which allows for the removal of the PCI bus as the main connection for the chipset. With the i815EP devices such as the IDE controller can gain a direct connection to the chipset without having to pass through the PCI bus.

Despite this new chipset design, the layout of i815EP based motherboards follows the same two chip principles as designs which use the older North and South Bridge architecture. The principle chip at the core of the i815EP is the i815 GMCH (Graphics, Memory Controller Hub) which looks after the CPU, main memory and the AGP 4X port.

The second chip used by the i815EP is the ICH2 (Integrated Controller Hub 2) which looks after the PCI bus, E-IDE controller (in this case U/DMA 100 compatible) BIOS and Audio & Modem codecs.

Like the Apollo Pro133A and i815e, the i815EP features support for PC-133 SDRAM as well as older PC-66 and PC-100 SDRAM. There is no support for VC-SDRAM as there is with VIA based chipsets. The biggest drawback as concerns memory support with the i815EP is the fact that it is limited to a maximum of only 512 MB main memory whereas the Apollo Pro133A can carry a maximum of 2 GB. Intel found that it had to limit the amount of memory which could be addressed by the i815e in order to accommodate the integrated i752 graphics controller, and has not seen fit to increase this despite the lack of an integrated i752 on the i815EP, which leads the author to think that it may only be disabled on the chipset and not in fact removed (this is similar to the math co-processor on the i486 SX).

There were proposals to release an enhanced version of the i815EP supporting up to 2 GB of PC-133 SDRAM to be called the i830, but this has now been stopped.

VIA KT133A page 2.

Intel i815EP page 2.